Typically, pressure vessels capable of containing liquids or gases at significant pressures have involved fixed shape cylinders or spheres formed of high-strength metals such as steel or aluminum. Such pressure vessels, while successful for their designed applications, involve a number of problems. First, such metallic cylinders are relatively heavy compared to the gases or fluids that they contain. Second, pressure cylinders contain all of the gas or liquid in a single space. Should the vessel rupture, the entire vessel is destroyed, often with a violent explosion sending shards of metal in all directions. Third, metallic cylinders have a definite shape and cannot be adapted to fit readily in many space-constrained applications. The present invention involves a number of small cells of an elongated tubular shape linked to each other by collecting end caps. The result of this design is that the pressure vessel may be readily formed into a variety of useful shapes to accommodate special applications. A pressure vessel of this type can be lightweight, adaptable to a variety of spaces and unusual applications, and is inherently safer in rupture situations.
A particular problem associated with pressure vessels operated at high pressure is the conditions under which they fail. Metallic cylinders are particularly dangerous in this regard as they may fragment suddenly if aged or fatigued from many use cycles, even if equipped with overpressure release devices. The present invention provides for a number of controlled pressure release mechanisms that are easily incorporated into the flexible pressure vessels.
The use of numerous small linked pressure vessels also present problems related to effectively joining such vessels together. The present invention provides for novel manufacturing methods for joining such cells.
Various designs have been developed using elongated tubular shaped vessels, most in the area of radiators and heat exchangers. U.S. Pat. No. 6,390,187 issued to Marechal et al. discloses a heat exchanger with flexible tubes. The tubes may be made from a plastic material and are designed to carry a heat-exchanging fluid capable of cooperating with an air stream circulating through the exchanger. The invention is intended to describe the method by which the tubes are maintained in parallel rows. The tubes are made from a plastic material and communicate by way of their extremities with two manifolds. The manifolds include collector plates equipped with apertures that thus form a means for holding the tubes in place. The tubes are arranged in rows that are parallel to one another by a distance corresponding to the tube thickness so that the various rows are adjacent in pairs of respective tubes of two consecutive pairs. The tubes generally exhibit a sinusoidal shape and thus aligned for expanding and contraction so that the tubes may utilize the flexible characteristics and maintain the integrity of the system.
U.S. Pat. No. 4,450,902 issued to Bosne, is directed to a heat exchanger in particular for an atmospheric cooling tower. The exchanger utilizes synthetic plastic material for the tubes that has one fixed header while the remainder of the exchanger is mounted by suspension to allow for free expansion. A chamber has a heat exchanger with a series of tubes extending throughout the length of chamber. The exchanger comprises a battery of smooth tubes made of a synthetic material. The tubes of the heat exchanger are fixed to the support structure at one of the ends and is freely suspended by a suspension members to allow for expansion and contraction.
U.S. Pat. No. 5,158,134, issued to Mongia et al., discloses a fully floating tube bundle. The exchanger comprises a plurality of fluid carrying tubes that is free floating with no direct contact between the end plates or center plate. Thus, the tubes are free to move with respect to the end plates and center plate as to eliminate damage by vibration and temperature changes.
U.S. Pat. No. 4,114,683 issued to Verlinden describes a flexible tube type fluid-fluid heat exchanger. The exchanger comprises a plurality of flexible synthetic tubes extending in a curved path between a pair of headers. The tubes are connected to headers and are constructed of a flexible plastic material so they may easily conform to the curvature of the wall 11.
U.S. Pat. No. 5,651,474 issued to Callaghan et al is directed to cryogenic structures that are vessels made of a durable plastic material and are adapted to contain cryogenic materials such as fuel. The structures are made of a fiber network impregnated with a matrix of thermal set plastics and have three tank lobes of a composite plastic reinforced with fibers. The tank lobes may be filament-wound on a rotating mandrel while the fibers are pre-impregnated with resin. Another technique is to heat the tank skins allowing the pre-impregnated fiber layers to fuse together and then cool so as to set up a solid matrix that grips the fibers.
While other variations exist, the above-described designs involving elongated tubular shaped vessels are typical of those encountered in the prior art. It is an objective of the present invention to provide a flexible pressure vessel that is capable of maintaining gasses or liquids at relatively high pressures. It is a further objective to provide this capability in a vessel that is light in weight and that presents a significantly reduced risk of injury in rupture situations. It is a still further objective of the invention to provide a pressure vessel that may be easily adapted to a variety of space constraints. It is yet a further objective to provide a pressure vessel that is durable, easily serviced, and that may be produced inexpensively.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.